ANALYSIS OF THE FACTORS DETERMINING THE SENSITIVITY OF A MINIATURIZEDGLUCOSE BIOSENSOR MADE BY CODEPOSITION OF PALLADIUM AND GLUCOSE-OXIDASE ONTO AN 8 MU-M CARBON-FIBER
H. Sakslund et al., ANALYSIS OF THE FACTORS DETERMINING THE SENSITIVITY OF A MINIATURIZEDGLUCOSE BIOSENSOR MADE BY CODEPOSITION OF PALLADIUM AND GLUCOSE-OXIDASE ONTO AN 8 MU-M CARBON-FIBER, Journal of electroanalytical chemistry [1992], 402(1-2), 1996, pp. 149-160
The preparation of miniaturized glucose biosensors by the electrochemi
cal codeposition of palladium and glucose oxidase (GOx) onto carbon fi
ber microelectrodes (8 mu m diameter) is described. The sensitivity of
the resulting sensors was dependent on the amount of palladium salt i
n the deposition solution, with the optimal performance found for 2.0
mg K2PdCl6 per 5 ml. This is approximately one order of magnitude lowe
r than found earlier (H. Sakslund et al. J. Electroanal. Chem., 374 (1
994) 71) during the preparation of a similar electrode system using a
glassy carbon disk (3 mm diameter). This difference in the optimal pal
ladium salt concentration probably reflects that mass transport to the
small cylindrical carbon fiber is more effective than to the large pl
anar glassy carbon electrode. The dependence on the amount of GOx and
the deposition time was similar for the two electrode systems, with th
e optimal response found when the amount of GOx was 26 mg or higher (p
er 5 mi) and the deposition time approximately 10 min. A long-term sta
bility test demonstrated that the sensitivity decreased to 50% of its
original value after 25 days and to 30% after 50 days. The morphology
of the electrode surfaces was characterized by scanning electron micro
scopy.